Hermetic MEMS Pressure Sensor with Integrated Ceramic Feedthroughs
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Solution Overview
Problem
Existing hermetic packaging for microelectromechanical systems (MEMS) pressure sensors faces challenges in maintaining long-term hermeticity and reliability, especially in biological environments, due to material interfaces and corrosion issues, which are exacerbated by miniaturization and the need for electrical feedthroughs.
Innovation Solution
A micromachinable, pico to nanoliter-volume pressure cavity constructed from high-purity ceramic materials with minimized material interfaces and hermetic electrical feedthroughs, fabricated using MEMS techniques, ensuring biocompatibility and durability, and allowing for reliable communication with external electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electrical feedthroughs are incorporated into hermetic packaging to enable signal transmission, then functionality is improved, but hermeticity and reliability deteriorate due to additional material interfaces that serve as potential leak sites
Solution Approach 1:
The patent merges the electrical feedthrough function with the hermetic seal structure by integrating the electrical contact directly into the bonding interface between substrates. This eliminates separate feedthrough components and their associated material interfaces, maintaining hermeticity while enabling signal transmission. The bonding interface itself serves dual purposes: mechanical joining and electrical conduction.
Solution Approach 2:
The bonding interface between substrates is designed to perform multiple functions simultaneously: mechanical support, hermetic sealing, and electrical signal transmission. This multi-functional design eliminates the need for dedicated feedthrough structures, reducing the number of material interfaces and potential leak sites while maintaining both hermeticity and electrical functionality.
2Volume of moving object
If miniaturization is pursued to reduce sensor size, then device dimensions are improved, but hermetic sealing reliability deteriorates as the total volume of material available for sealing shrinks
Solution Approach 1:
The patent combines mechanical bonding and hermetic sealing into a single integrated process. By using direct substrate bonding that simultaneously achieves mechanical strength and hermetic sealing, the design eliminates the need for separate sealing layers or adhesives. This reduces the total material volume required for sealing while maintaining reliability, enabling effective miniaturization.
Solution Approach 2:
The patent employs advanced bonding techniques that change the physical and chemical parameters of the substrate interfaces to achieve hermetic sealing with minimal material. By controlling bonding temperature, pressure, and surface preparation, the design achieves reliable hermetic seals in ultraminiature devices where traditional multi-layer sealing approaches would require excessive material volume.
3Reliability
If multiple material interfaces are used in feedthrough structures, then electrical connection is improved, but corrosion resistance deteriorates due to increased susceptibility to material degradation at interfaces
Solution Approach 1:
The patent merges electrical conduction and mechanical bonding functions into a single material interface, eliminating the need for multiple layered structures. This single integrated interface reduces the total surface area exposed to corrosive environments and eliminates galvanic corrosion risks between dissimilar materials, while maintaining reliable electrical connection through the bonding interface itself.
Data Source
AI summary
A pressure cavity is durable, stable, and biocompatible and configured in such a way that it constitutes pico to nanoliter-scale volume. The pressure cavity is hermetically sealed from the exterior environment while maintaining the ability to communicate with other devices. Micromachined, hermetically-sealed sensors are configured to receive power and return information through direct electrical contact with external electronics. The pressure cavity and sensor components disposed therein are hermetically sealed from the ambient in order to reduce drift and instability within the sensor. The sensor is designed for harsh and biological environments, e.g. intracorporeal implantation and in vivo use. Additionally, novel manufacturing methods are employed to construct the sensors.